The present invention relates to fluid flow control apparatus. The invention is particularly useful as an automatic shut-off valve, such as described in my prior U.S. Pat. Nos. 4,889,154 and 4,949,747, and is therefore described below with respect to such a valve.
The above patents describe automatic shut-off valves which open at a relatively high pressure and close at a relatively low pressure. Such valves are particularly useful in water pulsator devices including a housing having an inlet port formed with a restricted inlet orifice for receiving fluid in a continuous manner and at relatively low rate, and an outlet port formed with a larger orifice controlled by an outlet valve of the type described above, which opens at a relatively high pressure and closes at a relatively low pressure. Thus, water may be continuously introduced at a low rate into the housing, thereby increasing the pressure within the housing until the outlet valve opens, the opening of the outlet valve effecting a rapid discharge of the water thereby dropping the pressure within the housing until the outlet valve recloses.
One of the problems experienced in shut-off valves of the foregoing type particularly when used in water pulsator devices is the possibility that the outlet valve may partially open to discharge the fluid at a low rate and stabilize in this partially open condition. If this should occur, the device will continuously discharge the water at a low rate and therefore cease to act as a pulsator device.